[MFC] UNICODE和非UNICODE工程在UI上的区别

MFC工程最初是基于英文系统开发，由于外部DLL只提供了非UNICODE版本，为了开发方便将客户端系统设置为非UNICODE。近日由于要提供多语言支持。需要将工程设置为UNICODE，但是系统运行后，界面风格变了。

刚才以为是资源文件被修改了。经过网上多次google发现是stdafx.h里面的预编译语句导致的

#ifdef _UNICODE
#if defined _M_IX86
#pragma comment(linker,"/manifestdependency:\"type='win32' name='Microsoft.Windows.Common-Controls' version='6.0.0.0' processorArchitecture='x86' publicKeyToken='6595b64144ccf1df' language='*'\"")
#elif defined _M_IA64
#pragma comment(linker,"/manifestdependency:\"type='win32' name='Microsoft.Windows.Common-Controls' version='6.0.0.0' processorArchitecture='ia64' publicKeyToken='6595b64144ccf1df' language='*'\"")
#elif defined _M_X64
#pragma comment(linker,"/manifestdependency:\"type='win32' name='Microsoft.Windows.Common-Controls' version='6.0.0.0' processorArchitecture='amd64' publicKeyToken='6595b64144ccf1df' language='*'\"")
#else
#pragma comment(linker,"/manifestdependency:\"type='win32' name='Microsoft.Windows.Common-Controls' version='6.0.0.0' processorArchitecture='*' publicKeyToken='6595b64144ccf1df' language='*'\"")
#endif
#endif

如果采用UNICODE版本，上述代码将会执行。
在msddn中，#pragma comment用法如下：

#pragma comment( comment-type [,"commentstring"] )

linker
Places a linker option in the object file. You can use this comment-type to specify a linker option instead of passing it to the command line or specifying it in the development environment. For example, you can specify the /include option to force the inclusion of a symbol:
#pragma comment(linker, "/include:__mySymbol")
Only the following (comment-type) linker options are available to be passed to the linker identifier:
/DEFAULTLIB
/EXPORT
/INCLUDE
/MANIFESTDEPENDENCY
/MERGE
/SECTION

总而言之，语句“ #pragma comment(linker,"/manifestdependency:\"type='win32' name='Microsoft.Windows.Common-Controls' version='6.0.0.0' processorArchitecture='x86' publicKeyToken='6595b64144ccf1df' language='*'\"")”将导致连接器修改manifest文件中的外部依赖部分，从而让应用程序调用不同的系统控件。所以导致UI出现不同。